What percentage does oxygen make up in the compound MgSO_4?

1 Answer
Mar 12, 2017

Oxygen makes up 53.16%

Explanation:

In order to compute the mass percent of oxygen in MgSO_4 we're going to need two things:

color(purple)"1: The formula mass of the entire compound"
color(purple)"2: The atomic mass of oxygen"

The formula mass of MgSO_4 is 120.38 g/(mol)
1(24.31g/(mol)) + 1(32.07g/"mol") +4(16.00 g/"mol") = 120.38g/(mol)

The atomic mass of the oxygen atom is 16.00 g/(mol)

Now, we have to use the following equation:

http://www.chemieleerkracht.be/index.php/2-uncategorised/609-eee-375http://www.chemieleerkracht.be/index.php/2-uncategorised/609-eee-375

The numerator represents the mass of the desired atom, which is O in our case, and the denominator represents the mass of the entire compound. You just divide the two and multiply by 100 to obtain the percent composition:

"Mass of O"/("Molar Mass of "MgSO_4") xx100%

"(4)16.00 g/mol"/"120.38g/mol"xx100% = 53.16%

I multiplied the atomic mass of oxygen by 4 because you have to account for all of the oxygen atoms in the formula.